Automatic safety pilot burner



J K. CLARK April 4, 1939.

AUTOMATIC SAFETY PILOT BURNER Filed Sept. 17, 1936 2 Sheets-SheetIAAAAAF April 4, 1939. J CLARK 2,152,790

AUTOMATIC SAFETY PILOT BURNER Filed Sept. 17, 1956' 2 Sheets-Sheet 2 45"J/H 45 43 \1 w x Zmvcntor,

, Inna: K. Cums attorney Patented Apr. 4, 1939 PATENT OFFICE 2,152,790AUTOMATIC SAFETY PILOT BURNER James K. Clark, Utica, N. Y., assiznor toThe 'Partlow Corporation, New Hartford, N. Y., a

corporation of New York Application September 17, 1936, Serial No.101,241

6 Claims.

naces, ovens and the like.

A primary object of the invention is to provide a novel safety gas valveto shut off auto- 'matically the entire gas supply, in the event of afailure of gas, the extinguishment of a constantly burning pilot flame,or the failure of the electric current supply. The failure of any one ofthese might constitute a serious hazard,

if permitted to continue.

Another object is to provide new and useful electrical means to igniteautomatically the pilot burner and to turn on the main gas valve, inorder to initiate the heating cycles.

ll Another object is to provide an electrical system embodying spacedelectrodes, across which the current from the secondary winding of a,transformer may jump, in order to light the 'pilot burner.

Other objects of the invention will become more apparent as thedescription of the invention proceeds.

The preferred manner in which I desire to disclose my invention isherein shown in the accompanying drawings, in which:

Fig. 1 is a diagrammatic representation of the preferred form of afurnace heater equipped with electrical means for controlling the fuelsupply for both the furnace and the pilot burners;

Fig. 2 is a top plan view of the safety pilot burner;

Fig. 3 is a vertical section taken on the linev 3-3 of Fig. 2; and

Fig. 4 is a side elevation of the pilot burner, taken in the directionof the arrows shown in Fig. 2.

Referring now to the drawings in detail, I represents the source ofalternating current, which leads to the automatic safety pilot burner bymeans of a main line switch A, which leads to the primary winding A of astep-down transformer C, whose secondary winding 20 connects with thecoil of a series relay 2| which is provided with an armature 25. Thesecondary winding is also connected with a high voltage transformer C.

9 represents a switch of the double pole,

50 double throw, momentary contact type, which may be manually operatedby means of push button 2, to initiate the heating cycles. This switchcomprises two spaced arms or blades, connected by insulating cross-bars9', said blades 65 being pivoted respectively at contacts 4 and I0.

This invention pertains to gas-burning fur-' The blades are adapted tomake contact at one time with poles 3 and 8, and at another time withpoles I8 and 19. In the running position of the switch 9, the blades arekept in contact with poles l8 and I9 by means of the spring 5 I6; butwhen the blades are moved to the igniting position by pressing thebutton 2, the blades make contact with poles 3 and 8 and spring I6 isplacedunder tension. Immediately following the ignition cycle, and uponrelease 10 of pressure on button 2, the blades return to the poles l8and I! under the action of the spring l6. Band 13' represents solenoidoperated valves, which are operated to open position by solenoids butare self-closing. The valves are placed in branch pipes 34 and 29',forming branches of the main gas supply pipe 29. A

valve 34' is interposed in the b-wnch pipe 29' through which gas flowsto the main burner ll through a conventional gas and air mixer 3|. 20The valves 29" and 34' are intended for manually turning on and turningoil. the gas supply, to begin or end a heating interval.

The passage of current through the primary winding of transformer C,causes a low voltage to be induced in the secondary winding 20, said lowvoltage, the size or magnitude of the spark gap :0 and the main linevoltage hearing such a relationship to each other, that, if said inducedlow voltage be applied to the primary winding 30 of the transformer C, avoltage or potential will be set up in the secondary winding 23', ofsuch a value that it is incapable of jumping across the spark gap :1:when air alone is present within said spark gap. If full line voltage beapplied 35 to the primary or transformer C, a voltage or potential willbe set up in the secondary winding of the same, of such a value that itis capable of jumping across the same spark gap k a: when air alone ispresent within said spark gap. However, the presence of a flame withinthe spark gap a: will reduce the electrical resistance of the spark gap:1: to such an extent that when the aforesaid low voltage is applied tothe primary winding of the transformer C, the voltage induced in thesecondary winding 23' issumcient to cause a small current to flow in thesecondary winding and through the flame :c' and across the spark gap at.

' Thus, the removal or extinguishment of the pilot flame 3' causes thecessation of the electric current flow across the spark gap 2:.Furthermore, with the said small current flowing through the secondarywinding of the transformer C and through the flame and across the sparkgap 1:, the current flow in the circuit of the primary winding oftransformer C and the coil of the series relay 2| and the secondary rwinding 24 of transformer C is approximately larger than the current ofthe flame gas as is the turn ratio of transformer C. This current issufflcient to close the relay 2|, thus joining the armature 25 withcontacts 20 and 21 and completing a circuit from the electrical supplyat A to the solenoid valves B and B, energizing Should the 1 them andcausing them to open. pilot become extinguished, current could no longerpass across the gap at and the current flowing in the aforesaid circuitof the primary winding of C, the coil of the series relay 2| and thesecondary winding of C will be reduced to a very small amount due to thehigh resistshoe or impedence of the primary winding of when no currentis flowing in the secondary winding of same. This will cause the relayto open, thereby, breaking the circuits to the solenoid valves B and Band shutting off the entire gas supply.

The operation of the system is as follows:

When transformer C is energized by supplying current thereto from supplyA, push button 2 is pressed down, to cause the blades on switch 9 toloin the poles .I and 4 and poles 8 and ill. The circuit then extendsfrom source A to 3, through switch 9 to pole 4, thence to 5 and throughthe coil of the solenoid B to 8, thence back to 1 and to source A.During this interval, solenoid valve B is opened to admit gas fromsupply line 29, to the pilot burner 11. Simultaneously, another circuitis established from source A to pole 4, to pole III, to 22, through theprimary winding of transformer C to l2, to II and back to 1 and sourceA.

Current flowing in this latter circuit excites the transformer C toproduce a high voltageat II, to cause a spark to lump across the sparkgap 2: and thence to the pilot burner l1, through the metal gas pipe tothe ground connection on said pipe, and thence to the secondary windingof transformer C. 1

The passage of the spark at spark gap 3: ignites the gas at the pilotburner 11. Pressure on button 2 is suspended and switch 9 is returned tothe running position, that is, the blades connect poles 4 and I8 and I0and I9 respectively Current then feeds through the secondary winding 20,through the coil of the relay 2| to pole ID, to pole ID, to 22, throughthe primary winding 22 of C, to l2, through I! to 20. Since the pilotburner is ignited, a small current flows across the spark gap m, whichis suflicient to actuate the armature 25 of relay 2|, so that armature25 contacts 26 and 21, completing a circuit from source A to 26, to 21,to 28, through coil B to 6, to 1, to A. Simultaneously, another circuitis established from A to 26, to 21, to pole ii, to pole 4, to 5, throughcoil B, to 6, to 1, to A. These last mentioned circuits cause solenoidvalve B and B to open, admitting gas from the supply pipe 20, to thepilot burner I 1 and heating burner l1. This condition continues untilthe pilot burner is actually or accidentally extinguished, in whichevent, the current in the circuit 2|, 2|, 22, 23, I2, I2, is reduced tosuch an extent that the relay coil can no longer overcome the armaturespring whereupon contacts 26 and 21 are broken. This destroys thecircuits A, 25,

I 2', 21, 2|, 8, 'l, and A, 25, 2 6, 21, I8, 4, I, O, 1,

causing solenoids B and B to operateto close the valves and shut ofl thegas supply for the pilot and -main burner.

Solenoid valve B is held open by pressing button 2 of switch 9, and willclose during the period of time required for the switch 8 to pass fromthe ignite" position to the "run position, and for relay 2i to close.This is a very short interval of time but there is sufllcient residualgas remaining in the gas pipe between the solenoid valve and the pilotburner 11, to keep the latter ignited during this very brief interval.

By providing the type of switch shown at 2, it is seen that this switchfunctions constantly in one or more of the electrical safety pilotcircuits.

The pilot burner i1 (see Fig. 3) comprises a hollow body 30, which isformed with an upwardly facing internally and externally threaded nipple32, a lateral similarly threaded nipple 34 which is supplied ,with rawgas by the branch 34 of the pipe 28, and a downwardly facing internallythreaded opening 35 in which is disposed a porcelain insulator 36 thatprotects a metal electrode 31, that extends axially in the porcelain,and whose bottom end is equipped with a bindingpost 38 to which the linel5 connects and forms one side of the spark gap 1. The porcelain I8 isheld in place by a gland-nut 39, which threads into the bottom openingof the body 30. In order to further insulate the high tension electricalparts of the pilot burner l1, an inverted cupshaped cylindrical lavapart 40 whose reduced bottom end is threaded, screws into the nipple 32,which is axial to the porcelain 36. The top end of the electrode member31 is fitted with a spring 4|, which is capped with a washer 42 thatfrictionally engages the reduced lower end of a threaded metal conductorof terminal 43, having an axial gas passage or orifice 44, which formsone side of the spark gap 3:. This produces a continuous sole and freepassage for the gas delivered by the branch 34 of pipe 29. The spark gap1: is then completed by the top end 43' of the terminal 43 and aplurality of equally spaced metal electrodes 45, which are anchored in athreaded collar or nut 46 that screws onto the nipple 32. The upper endsof the electrodes are preferably equally spaced and bent inwardlyradially so as to facilitate the certain crossing of the gap as thevarious exigencies of the pilot burner arise. By the provision of therelatively large number of the electrodes 45 and the regular spacings oftheir free tips, a ring of metal is formed that alines axially'with theterminal 43, and the other insulating supports render failure of thepilot burner l1 practically impossible.

Having thus described my invention, what I claim is:

1. In combination, a pilot burner, spaced electrodes disposed adjacentto said pilot burner and adapted to have gas pass around and betweenthem, a heating burner capable of burning a mixture of gas and air, anelectrical control system for said pilot burner including anelectrically actuated valve for passing gas to said pilot burner, asecond electrical control system having included therein said spacedelectrodes and means for passing sparks across said electrodes forlgniting the gas flowing to said pilot burner, a third electricalcontrol system for said heating burner including an electricallyactuated valve for passing gas to said heating burner, when and onlywhen a flame is present at said pilot burner, said third electricalcontrol system including means controlled by the resistance offered bythe burning gas of said pilot burner between said electrodes for varyingall of said control systems to stop the operation of said burners, saidcontrol systems including a single biased rockable switch elementserving when operated in-one position to ignite said pilot burner andwhen operated in another position to maintain said pilot burner flameand the heating burner flame.

2. In combination, a pilot burner,- spaced electrodes disposed adjacentto said pilot burner and adapted to have gas pass around and betweenthem, a heating burner capable of burning a mixture of gas and air, anelectrical control system for said pilot burner including anelectrically actuated valve for passing gas to said pilot burner, asecond electrical control system having included therein said spacedelectrodes and means for passing sparks across said electrodes forigniting the gas flowing to said pilot burner, and a third electricalcontrol system for said heating bumer including an electrically actuatedvalve for passing gas to said heating burner, when and only when a flameis present at said pilot burner, said third electrical control systemincluding means controlled by the resistance offered by the burning gasof said pilot burner between said electrodes for varying all of saidcontrol systems to stop the operation of said burners, said controlsystems including a common switch serving when operated in one positionto ignite said pilot burner and when operated in another position tomaintain said pilot burner flame and the heating burner flame.

3. In combination, a pilot burner, spaced electrodes disposed adjacentto said pilot burner and adapted to have gas pass around and betweenthem, a heating burner capable of burning a mixture 01' gas and air, anelectrical control system for said pilot burnerincluding an electricallyactuated valve for passing gas to said pilot burn: er, a transformercapable at one time of supplying a high voltage and at another time alower voltage, said high voltage being of a value that electrodes when aflame is present atsaid pilot burner, a second electrical control systemhaving included therein said spaced electrodes and means for passingsparks across said electrodes for lgniting the gas flowing to said pilotburner, and a third electrical control system for said heating burnerincluding an electrically actuated valve for passing gas to said heatingburner, when and only when a flame is present at said pilot burner saidthird electrical control system including means controlled by theresistance ofi'ered by the burning gas at said pilot burner between saidelectrodes for varying all of said control systems to stop the operationof said burners.

4. The combination in accordance with claim 3, in which said controlsystems include a common switch serving when operated in one position toignite said pilot burner and when operated in another position tomaintain said pilot burner flame and the heating burner flame.

5. The combination in accordance with claim 3, in which said controlsystems include a single movable means in circuit therewith, servingwhen in one position to ignite said pilot burner and when in anotherposition to maintain said pilot flame and the heating burner flame.

6. The combination in accordance with claim 3, in which said controlsystems include a single spring biased rockable element in circuittherewith, serving when in one position to'ignite said pilot burner andwhen in another position to maintain said pilot flame and the heatngburner flame.

JAMES K. CLARK.

